<TITLE>fscanf</TITLE>
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<h3>SCANF(3)            Linux Programmer's Manual            SCANF(3)
</h3>

<h3>NAME
</h3>       scanf,  fscanf,  sscanf,  vscanf, vsscanf, vfscanf - input
       format conversion

<h3>SYNOPSIS
</h3>       #include &lt;stdio.h&gt;
       int scanf( const char *format, ...);
       int fscanf( FILE *stream, const char *format, ...);
       int sscanf( const char *str, const char *format, ...);

       #include &lt;stdarg.h&gt;
       int vscanf( const char *format, va_list ap);
       int vsscanf( const char *str, const char *format, va_list ap);
       int vfscanf( FILE *stream, const char *format, va_list ap);

<h3>DESCRIPTION
</h3>       The scanf family of functions scans input according  to  a
       format  as  described below.  This format may contain con-
       version specifiers; the results from such conversions,  if
       any,  are stored through the pointer arguments.  The scanf
       function reads input from the standard input stream stdin,
       fscanf  reads  input  from  the stream pointer stream, and
       sscanf reads its input from the character  string  pointed
       to by str.

       The vfscanf function is analogous to vfprintf(3) and reads
       input from the stream  pointer  stream  using  a  variable
       argument  list  of  pointers  (see  stdarg(3).  The vscanf
       function scans a variable argument list from the  standard
       input  and  the  vsscanf  function scans it from a string;
       these are analogous to the vprintf and vsprintf  functions
       respectively.

       Each  successive pointer argument must correspond properly
       with each successive conversion specifier (but  see  `sup-
       pression' below).  All conversions are introduced by the %
       (percent sign) character.  The format string may also con-
       tain other characters.  White space (such as blanks, tabs,
       or newlines) in the format  string  match  any  amount  of
       white  space,  including  none,  in the input.  Everything
       else matches only itself.  Scanning stops  when  an  input
       character  does  not match such a format character.  Scan-
       ning also stops when an input conversion  cannot  be  made
       (see below).

<h3>CONVERSIONS
</h3>       Following  the  % character introducing a conversion there
       may be a number of flag characters, as follows:

       *      Suppresses assignment.  The conversion that follows
              occurs as usual, but no pointer is used; the result
              of the conversion is simply discarded.

       h      Indicates that the conversion will be one of  dioux



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<h3>SCANF(3)            Linux Programmer's Manual            SCANF(3)
</h3>

              or  n  and the next pointer is a pointer to a short
              int (rather than int).

       l      Indicates either that the conversion will be one of
              dioux  or  n and the next pointer is a pointer to a
              long int (rather than int), or that the  conversion
              will  be  one  of  efg  and  the  next pointer is a
              pointer to double (rather than float).

       L      Indicates that the conversion will be efg  and  the
              next  pointer  is  a pointer to long double.  (This
              type is not implemented; the L  flag  is  currently
              ignored--this may not be true for Linux.)

       In addition to these flags, there may be an optional maxi-
       mum field width, expressed as a decimal  integer,  between
       the % and the conversion.  If no width is given, a default
       of `infinity' is used (with one exception, below);  other-
       wise  at most this many characters are scanned in process-
       ing the conversion.  Before conversion begins,  most  con-
       versions skip white space; this white space is not counted
       against the field width.

       The following conversions are available:

       %      Matches a literal `%'.  That is, `%%' in the format
              string  matches  a  single input `%' character.  No
              conversion is done, and assignment does not  occur.

       d      Matches  an  optionally signed decimal integer; the
              next pointer must be a pointer to int.

       D      Equivalent to ld; this exists  only  for  backwards
              compatibility.

       i      Matches  an  optionally  signed  integer;  the next
              pointer must be a pointer to int.  The  integer  is
              read  in base 16 if it begins with `0x' or `0X', in
              base 8 if it begins with `0', and in base 10 other-
              wise.   Only characters that correspond to the base
              are used.

       o      Matches an octal integer; the next pointer must  be
              a pointer to unsigned int.

       O      Equivalent to lo; this exists for backwards compat-
              ibility.

       u      Matches an optionally signed decimal  integer;  the
              next pointer must be a pointer to unsigned int.

       x      Matches an optionally a signed hexadecimal integer;
              the next pointer must be a pointer to unsigned int.




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<h3>SCANF(3)            Linux Programmer's Manual            SCANF(3)
</h3>

       X      Equivalent   to   lx;   this   violates   the  ANSI
              C3.159-1989 (``ANSI C'') but is backwards  compati-
              ble  with  previous UNIX systems--I don't know what
              Linux does with this.

       f      Matches an optionally signed floating-point number;
              the next pointer must be a pointer to float.

       e      Equivalent to f.

       g      Equivalent to f.

       E      Equivalent   to   lf;   this   violates   the  ANSI
              C3.159-1989 (``ANSI C'') but is backwards  compati-
              ble  with  previous UNIX systems--I don't know what
              Linux does with this.

       F      Equivalent to lf; this exists  only  for  backwards
              compatibility.

       s      Matches  a  sequence of non-white-space characters;
              the next pointer must be a pointer to char, and the
              array  must  be  large  enough  to  accept  all the
              sequence and the terminating  NUL  character.   The
              input string stops at white space or at the maximum
              field width, whichever occurs first.

       c      Matches  a  sequence  of  width  count   characters
              (default  1); the next pointer must be a pointer to
              char, and there must be enough  room  for  all  the
              characters  (no  terminating  NUL  is  added).  The
              usual skip of leading white  space  is  suppressed.
              To skip white space first, use an explicit space in
              the format.

       [      Matches a nonempty sequence of characters from  the
              specified  set  of  accepted  characters;  the next
              pointer must be a pointer to char, and  there  must
              be  enough  room  for  all  the  characters  in the
              string, plus  a  terminating  NUL  character.   The
              usual  skip  of  leading white space is suppressed.
              The string is to be made up of  characters  in  (or
              not in) a particular set; the set is defined by the
              characters between the open bracket [ character and
              a  close  bracket  ]  character.   The set excludes
              those characters if the first character  after  the
              open bracket is a circumflex ^.  To include a close
              bracket in the set, make  it  the  first  character
              after the open bracket or the circumflex; any other
              position will end the set.  The hyphen character  -
              is  also  special;  when  placed  between two other
              characters, it adds all intervening  characters  to
              the  set.   To  include  a hyphen, make it the last
              character before  the  final  close  bracket.   For



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<h3>SCANF(3)            Linux Programmer's Manual            SCANF(3)
</h3>

              instance,  `[^]0-9-]'  means  the  set  `everything
              except  close  bracket,  zero  through  nine,   and
              hyphen'.   The string ends with the appearance of a
              character not in the (or, with  a  circumflex,  in)
              set or when the field width runs out.

       p      Matches  a  pointer  value  (as  printed by `%p' in
              printf(3); the next pointer must be  a  pointer  to
              void.

       n      Nothing is expected; instead, the number of charac-
              ters consumed thus far from  the  input  is  stored
              through  the  next pointer, which must be a pointer
              to int.  This is not a conversion, although it  can
              be suppressed with the * flag.

       For  backwards  compatibility, other conversion characters
       (except `\0') are taken as if they were `%d' or, if upper-
       case, `%ld', and a `conversion' of `%\0' causes an immedi-
       ate return of EOF.   The  F  and  X  conversions  will  be
       changed in the future to conform to the
        ANSI  C  standard,  after  which  they  will act like and
       respectively.  The behavior of Linux on  the  non-standard
       points is not known by this documenter.


<h3>RETURN VALUES
</h3>       These functions return the number of input items assigned,
       which can be fewer than provided for, or even zero, in the
       event  of  a matching failure.  Zero indicates that, while
       there was input available, no conversions  were  assigned;
       typically  this is due to an invalid input character, such
       as an alphabetic character for  a  `%d'  conversion.   The
       value  EOF  is  returned if an input failure occurs before
       any conversion such as an end-of-file occurs. If an  error
       or end-of-file occurs after conversion has begun, the num-
       ber of conversions which were  successfully  completed  is
       returned.

</pre>
<hr>
<h3>SEE ALSO
</h3><p>
<a href=strtol.htm>strtol</a>, 
<a href=strtoul.htm>strtoul</a>, 
<a href=strtod.htm>strtod</a>, 
<a href=getc.htm>getc</a>, 
<a href=printf.htm>printf</a>, 
<pre>

<h3>STANDARDS
</h3>       The  functions  fscanf,  scanf, and sscanf conform to ANSI
       C3.159-1989 (``ANSI C'').

<h3>BUGS
</h3>       Differences for Linux are not known  at  this  time.   The
       following is for the BSD version:

       The current situation with %F and %X conversions is unfor-
       tunate.

       All of the backwards compatibility formats will be removed



<h3>BSD MANPAGE              29 November 1993                       4
</h3>




<h3>SCANF(3)            Linux Programmer's Manual            SCANF(3)
</h3>

       in the future.

       Numerical  strings  are  truncated  to 512 characters; for
       example, %f and %d are implicitly %512f and %512d.





















































<h3>BSD MANPAGE              29 November 1993                       5
</h3>

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